A magneto-optical recording disk memory has been put to practical use as a rewritable optical memory. However, the conventional magneto-optical recording disk memory is disadvantageous in that the reproduction characteristics thereof are deteriorated when the diameter of a recorded bit and the distance between adjacent recorded bits become smaller than the diameter of a condensed semiconductor laser beam. This is because the adjacent recorded bits enter into the spot of a condensed laser beam, thereby to prevent each recorded bit from being reproduced as separated from the adjacent recorded bits.
To overcome such a defect, Japanese Patent Laid-Open Publication No. 4-255941 proposes a magnetic super resolution technology using a magneto-optical recording medium comprising a reproducing layer, an auxiliary reproducing layer and a recording layer. More specifically, this magneto-optical recording medium is previously initialized such that the magnetization direction in the reproducing layer is arranged in one direction, and the upstream and downstream recorded bits with respect to the light beam spot are then masked by the reproducing layer, such that each bit recorded at a pitch narrower than the width of the light beam spot, can be reproduced.
However, the technology above-mentioned requires a magnetic field for previously initializing the magnetization direction in the reproducing layer, causing the recording and reproducing apparatus to be increased in size.
In view of the foregoing, Japanese Patent Laid-Open Publication No. 5-81717 proposes a super resolution reproducing technology using a magneto-optical recording medium of a two-layer structure having (i) a reading layer which is an in-plane magnetized layer at room temperature and which becomes a perpendicularly magnetized layer with a rise in temperature, and (ii) a recording layer which is a perpendicularly magnetized layer. According to this technology, each recorded bit smaller than the diameter of a laser beam can be reproduced as separated from the adjacent recorded bits without the reproducing layer initialized.
In recording image information or the like, there is desired a recording and reproducing apparatus having a much larger capacity. In the conventional magneto-optical recording medium above-mentioned, however, information cannot disadvantageously be recorded with high density required for increasing the recording capacity.